Aircraft typically include a plurality of flight control surfaces that, when controllably positioned, guide the movement of the aircraft from one destination to another. The number and type of flight control surfaces included in an aircraft may vary, but typically include both primary flight control surfaces and secondary flight control surfaces. The primary flight control surfaces are those that are used to control aircraft movement in the pitch, yaw, and roll axes, and the secondary flight control surfaces are those that are used to influence the lift or drag (or both) of the aircraft. Although some aircraft may include additional control surfaces, the primary flight control surfaces typically include a pair of elevators, a rudder, and a pair of ailerons, and the secondary flight control surfaces typically include a plurality of flaps, slats, and spoilers.
The positions of the aircraft flight control surfaces are typically controlled using a flight control surface actuation system. The flight control surface actuation system, in response to position commands that originate from either the flight crew or an aircraft autopilot, moves the aircraft flight control surfaces to the commanded positions. In most instances, this movement is effected via actuators that are coupled to the flight control surfaces. Though unlikely, it is postulated that a flight control surface actuator could become inoperable. Thus, some flight control surface actuation systems are implemented with a plurality of actuators coupled to a single flight control surface.
In many flight control surface actuation systems, the flap actuators and the slat actuators are each driven via a central power drive unit and mechanical drive trains. For example, many flight control surface actuation systems include a central flap power drive unit that drives each of the flap actuators via a plurality of gears and either torque tubes or flexible shafts. Some flight control surface actuation systems similarly include a central slat power drive unit that drives each of the slat actuators via a plurality of gears and either torque tubes or flexible shafts. Alternatively, some flight control surface actuation systems include individual power drive units that individually drive each of the flap and or slat actuators.
The flight control surface actuation systems that use central flap and slat drive units, or that use individual flap and slat actuator power drive units, are generally safe, reliable, and robust. However, these systems do suffer certain drawbacks. Namely, these systems can be relatively complex, can involve the use of numerous parts, and can be relatively heavy. Moreover, the flight control surface actuation systems that use individually driven flap and slat actuators typically rely on numerous controllers, such as one per actuator or flight control surface, which can further increase complexity and weight.
Hence, there is a need for a flight control surface actuation system that is less complex and/or uses less components and/or is lighter than current systems that are used to drive the aircraft flap and slat actuators. The present invention addresses one or more of these needs.